Field of the Invention
The present invention relates to a conductive polymer composition containing a π-conjugated conductive polymer, a coated article using the same, and a patterning process.
Description of the Related Art
Conventionally, in the fabrication process of a semiconductor device such as IC and LSI, microprocessing by lithography using a photoresist has been employed. This is a method of etching a substrate by using a resist pattern as a mask, in which the resist pattern is obtained by irradiating a thin-film with light to induce crosslinking or decomposition reaction, thereby remarkably changing the solubility of the thin-film, and subjecting the same to development treatment with a solvent or the like. In recent years, as a semiconductor device advances toward high integration, high-precision microprocessing using a beam with short wavelength have been required. The development of lithography using electron beam has been progressed for next generation technique because of its short-wavelength properties.
The lithography using electron beam has a specific problem of electrification phenomenon (charge-up) during exposure. This is a phenomenon that when a substrate to be irradiated with electron beam is coated with an insulating resist film, it is charged by accumulation of electric charge on or in the resist film. An orbit of incident electron beam is bent by the electrification, and therefore the precision of drawing is significantly reduced. Accordingly, an antistatic film to be applied on an electron beam resist has been investigated.
In the lithography using an electron beam, accurate positioning has been more important in an electron beam drawing of a resist due to miniaturization to <10 nm generation. As the drawing technology, it has been developing an enhancement of current in prior arts, MBMW (multi beam mask writing), and so on, and it is presumed that the resist will be electrified more severely thereby. Accordingly, a conductive polymer with lower resistivity and higher ability to discharge the charge is required as a means to improve the antistatic performance of an antistatic film coping to the development of drawing technology from now on.
In order to suppress lowering of drawing accuracy due to electrification phenomenon on a resist, Patent Document 1 discloses that the resist is coated with a π-conjugated conductive polymer having an introduced acidic substituent in the structure, and thus formed conductive polymer film shows an antistatic effect in electron beam drawing, thereby dissolving various faults due to electrification such as a deformation of a resist pattern or an electrostatic adverse effect to accurate positioning of lithography in an electron beam irradiation. It is also revealed that the conductive polymer film retains water solubility even after electron beam drawing with high irradiation dosage, and accordingly can be removed by water washing.
Patent Document 2 discloses a composition composed of a polyaniline base conductive polymer, polyacid, and H2O; and reveals that when the composite composed of a polyaniline base conductive polymer and polyacid is 5 to 10% by mass, the spin coat-film forming can be favorably performed, and in addition to this, when the film thickness is 150 nm, antistatic performance is observed, thereby forming an antistatic film which can be peeled and washed with H2O.
The π-conjugated conductive polymer is also used for a device constituent component in a laminated organic thin-film device, other than the foregoing antistatic film use, due to the thin-film forming property. In a device composed of a laminated thin-film structure, the formed conductive thin-film can be used as a carrier implanted layer, which is laminated onto the upper-layer of a film electrode (an application-type transparent electrode) or an electrode (mainly at an anode side, such as a transparent electrode) and has an effect to reduce the transfer barrier of a carrier from the electrode, and as a carrier transferring layer to transfer carriers to an emission layer for an emission phenomenon.
Previously, in organic EL illumination devices or organic EL displays, metal oxides such as ITO with high conductivity and transparency have been used for electrode surfaces to supply electricity to device structures. The ITO, however, contains indium, which is rare metal; and is constructed as an electrode surface by vapor deposition process, thereby having a limit in upsizing of a device or improving the productivity. Accordingly, it has been required for developing a conductive material which is low cost and can form larger surface by a simpler surface-forming method with high productivity.
Since inorganic materials such as ITO do not have flexibility, it is difficult to be applied to prospective flexible laminated organic thin-film devices. Accordingly, in order to make a device have such additional functions in the future, it requires a material for a device constituent component with durability for curvature.
As compared to the foregoing inorganic transparent electrode materials such as ITO, π-conjugated conductive polymers have flexibility after film-forming, and the film-forming method thereof can include a wet process such as spin coating or printing. In film-forming by a wet process, the film-forming time can be shortened compared to dry processes such as vapor deposition, sputtering, and CVD even in the case of single wafer application such as spin coating. When the film-forming can be performed by Role to Role printing onto a flexible substrate, the productivity is tremendously improved, and increasing the area is accelerated.
In the laminated organic thin-film devices, the π-conjugated conductive polymer functions not only as a substituted material for ITO, but also as a carrier implanted layer or a carrier transferring layer in accordance with a device structure. In a laminated structure of a device, the carrier implanted layer is located onto an upper-layer of an electrode surface, and the carrier transferring layer is located between the carrier implanted layer and an emission layer for emission or between an electrode surface and the emission layer. In construction of a device, the foregoing are laminated successively onto a substrate beginning with the outmost layer of the device structure.
In the construction of the laminated organic thin-film devices, a wet process is very effective for film-forming and laminating each constituent component. In a process to laminate a particular layer onto an under-layer film, however, the under-layer have to be composed of a material which is not dissolved or peeled by the solvent of the upper-layer. That is, it is necessary to meet a condition in which the solid content of material forming each layer is not dissolved into the solvent of a material forming the adjoined layer.
In the laminated organic thin-film devices, the layers are in surface contact so as to transfer carriers between each laminated layer in high efficiency. When there occurs transference of a substance other than the carrier between the contact surfaces or mixing of each constituent component at the interface, they influence the degradation life of a device. Accordingly, each material has to be structured so as to contact with each other without interaction between each constitution layer, and the material is required to meet the condition.